The CMS silicon strip tracker

The silicon strip tracker (SST) is a key element of the CMS Tracking System. It consists of five cylindrical layers and of six mini-disks of microstrip-silicon sensors in the barrel region and of ten disks per side in the forward region; an SST overview is given. After a brief introduction on the general tracking requirements in terms of momentum resolution, tracking efficiency and vertex capability, we discuss the physical requirements and experimental constraints for the SST. The basic functional sub-unit of the system, the module, together with its active elements, the sensors, are also described.